Can a new structural crack suggest F-35 is healthier?

When an aluminium alloy bulkhead inside the Lockheed Martin F-35B cracked last year after just 1,600h of durability tests, the programme was caught by surprise. Lockheed's analysis had not predicted the 496 bulkhead would buckle before the end of the 16,000h-long durability exam.

A year later, the programme claims to have made some progress.

Unfortunately the airframe structure is still not immune from early cracking, but this time Lockheed was not caught by surprise.

Lockheed's analysis predicted root rib forgings in each wing for the F-35A and F-35B also would fail, and they actually survived slightly longer than expected, the programme office says. The root rib actually succumbed after about 2,800h of the 16,000h durability test.  Lockheed had already designed a fix to install in the next lot of low-rate initial production (LRIP).